Synthetic insulation with microporous membrane

ABSTRACT

An insulation package and method ° fibrillation including a functional layer, a breathable water repellant insulating layer, and a highly breathable microporous membrane layer having a network of pores. The functional fabric, the highly breathable insulating layer and the microporous membrane layer are laminated to one another to form a waterproof breathable insulated fabric.

This application is a continuation of U.S. patent application Ser. No.10/732,692 filed Dec. 9, 2003, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to waterproof breathable insulationmaterial and in particular such material for use in outdoor clothing andboots.

2. Description of the Related Art

Outdoor enthusiasts have continually demanded technically advanced gearto protect themselves from the elements. This demand resulted in thedevelopment of several waterproof, breathable fabric constructions wherethe fabric is typically laminated to thin films or membranes. Waterproofbreathable fabrics have been used in performance garments for manydecades and have proven to be a preferred performance component. Boththe prevention of water reaching the body from outside the clothing, andthe removal of vapor produced by the body are of great importance to thewearer in terms of comfort. However, the disadvantage to such fabricshas always been that although they are classified as being breathable,they do not offer significant moisture vapor transport. Further, mostbreathable fabrics tend to have very limited insulating properties.Still further, fabrics laminated to certain types of membrane types tendnot be very flexible and generate noise when in use. Accordingly,despite their claims most waterproof breathable fabrics tend to be lessbreathable than desired, offer limited insulating properties so thatthey must he used in conjunction with some form of insulating material,and require the user to endure their stiff and noisy nature.

Insulating materials are often used in conjunction with or incorporatedinto performance garments to provide for thermal protection. However,most insulating materials do not provide for water repellency oralternatively provide water repellency at the cost of a correspondingdiminution in thermal protection. PrimaLoft® insulation, as described inU.S. Pat. Nos. 4,992,327 and 4,588,635 and incorporated herein byreference, is unique to the synthetic insulation world in that it offerssuperior water repellency in addition to the thermal performanceindicative of the micro and fine fiber construction.

However, PrimaLoft® insulation has been primarily used as a replacementfor natural down with the added benefit that it is waterproof.Alternatively, PrimaLoft® batt has incorporated into clothingmanufacture where it is a separate insulating layer. Often it ismechanically secured to other layers of woven or non-woven material forexample through quilting. However, the PrimaLoft® insulation by itselfdoes not have sufficient structural integrity, or aesthetic appearanceto suffice as both an insulating material and an outer garment layer.

Another element of many waterproof breathable fabrics are monolithicmembrane films, which are used to impart a breathable barrier to thefabric. Monolithic membranes promote the permeation of water vaporthrough the use of a hydrophilic polymer layer which absorbs the waternext to skin and transmits it to the external environment.

Unfortunately, monolithic films typically experience significantswelling of the hydrophilic layer which significantly alters the vaporremoval characteristics of the film and the comfort for the user.Further, although this type of membrane also has a very high tearstrength, which is generally favorable in performance fabrics, this alsoresults in extraordinary stiffness in a garment that is usually notviewed as a positive attribute.

Accordingly, there is a need for an waterproof, breathable, insulationmaterial which provides superior water repellency or waterproofingcharacteristics coupled with superior vapor removal characteristicswhich will not swell and has sufficient tear strength, but which is notunduly stiff or noisy for the wearer.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed to an insulation packagehaving a functional fabric layer, a highly breathable microporousmembrane layer having a network of pores, and a breathable waterrepellant insulating layer. The layers being laminated to one another toform a waterproof breathable insulated fabric.

In another embodiment of the present invention the insulating layer is abreathable water repellant insulating layer is in the form of a cohesivefiber structure, which structure comprises an assemblage of:

-   -   (a) from 70 to 95 weight percent of synthetic polymeric        microfibers having a diameter of from 3 to 12 microns; and    -   (b) from 5 to 30 weight percent of synthetic polymeric        macrofibers having a diameter of from 12 to 50 microns.

The present invention is also directed to a method of forming awaterproof insulation package. The steps include providing a first layerof functional fabric, a second layer of microporous membrane, and athird layer of breathable water repellant insulation. Further the firstlayer is bonded to the second layer, and the second layer to the third.

The various features novelty which characterize the invention arepointed out in particularity in the claims annexed to and forming a partof this disclosure. For a better understanding of the invention, itsoperating advantages and specific objects attained by its uses,reference is made to the accompanying descriptive matter in whichpreferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, reference is made tothe following description and accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a waterproof insulation packageaccording the present invention; and

FIG. 2 is a cross-sectional view of another waterproof breathableinsulation package according the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings, the present invention is directed towardsan insulation package 10 shown generally in FIG. 1 that is bothwaterproof and breathable. As shown in FIG. 1 an insulating package 10is comprised of an insulating material 12, a microporous membrane 14,and a functional fabric 16. The insulating material 12, the microporousmembrane 14 and the functional fabric 16 are bonded to one another,preferably through known lamination techniques. In a preferredembodiment, the laminated package 10 consists of PrimaLoft® insulationas the insulating material 12 and any woven, non-woven, fleece, or otherfabric structure as the functional fabric 16 adhered or laminated to thesurface of the microporous membrane 14, which is itself laminated to thePrimaLoft® insulation. In certain situations it may be desirable to addan additional layer of functional fabric or a liner to the nonmicroprousmembrane side of the insulation material 12.

A microporous membrane 14 is preferred because it is has a highlybreathable interconnected network of micropores that can be manipulated.The breathability and air permeability properties of the microporousmembrane 14 are selectively defined through stretching and manipulationof the membrane. This stretching alters the original membrane pore size.Further, the microporous membrane lends itself to applications usinglamination techniques.

In application a pore network of the microporous membrane is constructedso that the work path and size of the pores permit the optimal transferof moisture vapor while still inhibiting the transfer of water, yet notat the level acceptable for consideration as a waterproof, breathablemembrane.

One of the advantages of the microporous membrane 14 is that it does notabsorb water or exhibit swelling. Monolithic membranes of the prior artare typically polyurethane based function through the solubility ofwater molecules in the membrane layer. As a result, despite theirgeneral resistance to tearing, they are less desirable as they are proneto swelling. Such swelling is known to alter the hydrophilic propertiesof the monolithic membranes.

In contrast, microporous membranes function through the diffusion ofmoisture vapor across the pores. Typical pore size is, for example,between 1 and 8 μm. Because of this pore size, the microporous membraneof the present invention is not itself considered waterproof orhydrophobic. Further, microporous membranes are typically formed ofpolytetraflourethylene or other polymeric material with a lowcrystalinity (generally less than 30%). In addition the polymericmaterial may be blended with an inorganic filler with a particle size of0.5-5 μm. A microporous membrane may generally have a thickness ofapproximately between 30 and 50 μm. Importantly, such microporousmembranes do not experience the swelling common of monolithic membranes.

Further, by laminating the insulating layer 12 to a microporous membrane14 the resistance to tearing of the microporous membrane, which isgenerally less than that of monolithic membranes, is greatly increased.In addition, the stiffness of the combination is significantly less thanthat created by the bonding of an insulating material to a monolithicmembrane.

To further enhance the waterproof nature of the insulation package thefunctional layer 16 may be coated with a durable water repellanttreatment or cire coating.

According to one aspect of the present invention, the insulating layer12 is a synthetic fiber thermal insulator material in the form of acohesive fiber structure, which structure comprises an assemblage of:

-   -   (a) from 70 to 95 weight percent of synthetic polymeric        microfibers having a diameter of from 3 to 12 microns; and    -   (b) from 5 to 30 weight percent of synthetic polymeric        macrofibers having a diameter of from 12 to 50 microns,    -   wherein at least some of the fibers are bonded at their contact        points, the bonding being such that the density of the resultant        structure is within the range 3 to 16 kg/m³ (0.2 to 1.0 lb/ft³),        the bonding being effected without significant loss of thermal        insulating properties of the structure compared with the        unbonded assemblage.

Microfibers and macrofibers for use in the present invention may bemanufactured from polyester, nylon, rayon, acetate, acrylic, modacrylic,polyolefins, spandex, polyaramids, polyimides, fluorocarbons,polybenzimidazols, polyvinylalcohols polydiacetylenes, polyetherketones,polyimidazols, and phenylene sulphide polymers such as thosecommercially available under the trade name RYTON.

The bonding may be effected between at least some of the macrofibers toform a supporting structure for the microfibers, or may be between bothmacrofibers and microfibers at various contact points. The macrofibersmay be selected from the same material or from a variety of materialsand may be either the same material as the microfibers or different.

In one advantageous embodiment of the invention microfibers are formedfrom polyethylene terephthalate and the macrofibers are selected fromthe polyethylene terephthalate or a polyaramid, such, for example,commercially available under the trademark “Kevlar”.

The macrofibers can be monofibers, i.e., fibers having a substantiallyuniform structure or they may be multi-component fibers having a moietyto facilitate fiber to fiber bonding. The fiber may he a fiber mixturein which at least 10% by weight comprises macrofibers of a lower meltingpoint thermoplastic material to assist the fiber to fiber bonding. In afurther embodiment of the invention the macrofibers may be a fibermixture comprising multi-component macrofibers and a monocomponentmacrofiber capable of bonding one with the other and/or with themicrofibers.

In another embodiment of the present invention the macro component fibermay be a mix or blend of macrofibers having different properties, forexample, a macrofiber mix may comprise two or more different fibers suchas a polyester fiber to give the desired bonding and a “Kevlar” fiber togive stiffness. The proportion of stiffening fiber to bonding fiber maybe varied to provide different properties subject to the requirementthat the proportion of bondable fibers is sufficient for the macrofiberstructure to provide an open support for the microfibers as hereinafterdescribed.

Some materials, such as, for example, polyphenylene sulphide fibers,aromatic polyamides of the type commercially available under the tradename “APYIEL”, and polyimide fibers such as those manufactured byLenzing AG of Austria, exhibit flame retardant properties or arenonflammable. Such materials can, therefore, confer improved flame orfire resistant properties on manufactured products containing thematerials in accordance with the present invention.

The bonding of the fibers of the insulting layer 12, in accordance withone aspect of the invention, is preferably, principally between thefibers of the macrofiber component at their contact points. The purposeof the macrofiber to macrofiber bonding is to form a supportingstructure for the micro-fiber component, said supporting structurecontributing significantly to the mechanical properties of theinsulating material. By bonding the macrofibers, the macrofibersmaintain an open bonded fiber structure within which the microfibers canbe accommodated. Alternatively, the macrofibers and/or the microfibersmay be bonded at their contact points.

Any means of bonding between the macrofibers may be employed such, forexample, as by the addition of solid, gaseous or liquid bonding agentsor preferably through the application of heat to cause the lowertemperature fiber component to melt and fuse at contact points.

The method of bonding the components of the insulating layer 12 is notcritical, subject only to the requirement that the bonding should becarried out under conditions such that neither fiber component loses itsstructural integrity. It will be appreciated by one skilled in the artthat any appreciable change in the macro- or microfibers during bondingwill affect the thermal properties adversely; the bonding step needs,therefore, to be conducted to maintain the physical properties anddimensions of the fiber components and the assemblage as much aspossible.

The thermal insulating properties of the bonded insulating layer 12 arepreferably substantially the same as, or not significantly less than,thermal insulating properties of a similar unbonded assemblage.

In a particular embodiment of the present invention bonding within theinsulating layer 12 may be affected by heating the fibers for a time andat a temperature sufficient to cause the fibers to bond. Such heatingperiod may be at a temperature of from about 125° C. (257° F.) to 225°C. (437° F.) for a period of the order of 1 minute to 10 minutes andpreferably at a temperature of from about 140° C. (284° F.) to 200° C.(392° F.) for a period of about 3 to 7 minutes; these periods are, ofcourse, dependent upon the materials of the fiber component mix.

PrimaLoft ® as described above is suitable for lamination applications.When produced as a batt, a surface on the batting structure can becreated such that it is conducive to being laminated with an outer shellfabric for use as a garment or sleeping bag or with a microporousmembrane as described herein. Lamination techniques require asubstantially smooth surface on the insulation for application andsustainability of adhesion to a fabric.

This smooth surface can be created through processes known in the artsuch as IR calendaring, hot plate calendaring, heated rollers, resincoatings, and/or unique hot air oven processing (unique being defined astemperature and air flow manipulation). In addition to surfacetreatments, the internal structure of the batting needs to be wellbonded in order to maintain the integrity of the structure throughrepeated use and laundering of a laminated article without delamination.

Although in the preferred embodiment a Primaloft® insulation, and inparticular a batt material formed of Primaloft ® is used, it should beunderstood that other insulating materials can be used without departingfrom the scope of the present invention.

Experimental Data

This insulation package 10 provides water protection above 2.0 psihydrostatic pressure according to AATCC Test Method 127 titled, “WaterResistance: Hydrostatic Pressure Test.” It is typically accepted in theoutdoor garment industry that any fabric with a hydrostatic pressurecapability above 2.0 psi be considered waterproof by definition. AATCCis the abbreviation for the American Association of Textile Chemists andColorists. AATCC 127 is a test method that measures the resistance of afabric to the penetration of water under hydrostatic pressure and isapplicable to all types of fabrics. One surface of the test specimen issubjected to pressurized water where the pressure is increasing at aconstant rate until three points of leakage are observed on the otherside of the specimen. In one experiment, the insulation package 10utilizing a Primaloft® batt as the insulating layer 12 was found to havea resistance to hydrostatic pressure that exceeded 185 cm-H₂O or 2.63psi. Accordingly, the insulation package 10 was found to exhibit waterresistance characteristics that far exceeded that necessary to beconsidered waterproof.

Another test performed on the insulation package was a determination ofthe Water Vapor Transmission Rate (WVTR). This was done in accordancewith ASTME 96-00 Procedure E. The WVTR is a test to determine the amountof water vapor that can pass through the fabric over a given period.

For example, one known microporous membrane often cited in the prior artas a basis for comparison and control in experiments is CELGARD® 2500which is known to have a WVTR of 5000 g/m²/24 hrs.

Breathable outerwear garments of the prior art such as that described inExample 1 of U.S. Pat. No. 6,100,208 having a first layer ofmulticomponent fibers a second layer of multicomponent fibers and awater impermeable barrier in between formed of low density polyethylenehave been shown to have a MVTR of 3465 g/m²/24 hrs. However, the garmentdescribed in the '208 patent does not provide an insulating layer asthat of the present invention. It would be expected that the addition ofan insulating layer would decrease the WVTR of the outdoor fabric.

The test of the insulating package of the present invention wasperformed at 37.8° C. and at 90% relative humidity. In this test asample of laminated SUPPLEX fabric, microporous membrane material, andPrimaloft® insulation, as described in the present invention achieved atWVTR of 3521 g/m²/24 hrs. This is significant because the test sampleprovides an insulating layer not present in the two examples describedabove, yet has greater MVTR than the un-insulated laminate outdoorfabric and nearly as great an MVTR as the microporous membrane byitself. As such the insulating package of the present inventiondemonstrates that a wearer of clothing constructed using the insulationpackage should expect to remain in reasonable comfort despitesignificant athletic activity.

It has thus be shown that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,because certain changes may be made in carrying out the above method andin the construction(s) set forth without departing from the spirit andscope of the invention, it is intended that all matter contained in theabove description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. An insulation package comprising: at least onefunctional fabric layer or exterior side of the insulation package; abreathable water repellant insulating layer on an interior side of theinsulation package; and a highly breathable, air permeable microporousmembrane layer having a network of pores, disposed between said at leastone functional fabric layer and said breathable water repellantinsulating layer; wherein the functional fabric, microporous membranelayer and the insulating layer, are laminated to one another throughoutthe entire insulation package to form a waterproof breathable insulatedfabric, wherein the functional fabric, microporous membrane layer andthe insulating layer, are laminated to one another to form a waterproofbreathable insulated fabric.
 2. The insulation package of claim 1,wherein at least one of the at least one functional fabric layers is awater resistant fabric.
 3. The insulation package of claim 2, whereinthe functional fabric layer is coated with a cire coating.
 4. Theinsulating of claim 1, further comprising a second functional fabriclayer.
 5. The insulating package of claim 4, wherein the secondfunctional fabric is laminated to the insulating layer on thenon-membrane side.
 6. The insulation package of claim 1, wherein thesize of a pore in the network of pores is defined by stretching themicroporous membrane.
 7. The insulation package of claim 1, wherein saidinsulation package permits vapor transfer and inhibits water transfer.8. The insulation package of claim 1, wherein the breathable waterrepellant insulating layer is nonwoven and comprises fibers selectedfrom the group consisting of microfibers, macrofiber, natural fibers,and blends thereof.
 9. The insulation package of claim 1, wherein thebreathable water repellant insulating layer is woven and comprisesfibers selected from the group consisting of microfibers macrofiber,natural fibers, and blends thereof.
 10. The insulation package of claim1, wherein the breathable water repellant insulating layer has acohesive fiber structure comprising an assemblage of: (a) from 70 to 95weight percent of spun and drawn, synthetic polymeric microfibers havinga diameter from 3 to 12 microns; and (b) from 5 to 30 weight percent ofsynthetic polymeric macrofibers having a diameter of 12 to 50 microns.11. The insulation package of claim 1, wherein the breathable waterrepellant insulating layer formed as a batt having a smooth surfacecompatible for lamination techniques.
 12. The insulation package ofclaim 11, wherein the smooth surface is formed by at least one processselected from the group consisting of IR calendaring, hot platecalendaring, using heated rollers, resin coatings, and hot air ovenprocessing.
 13. The insulation package of claim 1, wherein thefunctional fabric is selected from the group consisting of fleece,woven, and nonwoven fabrics.
 14. A method of forming a waterproofinsulation package according to claim 1, the method comprising the stepsof: providing a first layer of functional fabric on an exterior side ofthe insulation package; providing a second layer of microporous membranedisposed between said at least one functional fabric layer and saidbreathable water repellant insulating layer; providing a third layer ofbreathable water repellant insulating layer on an interior side of theinsulation package; bonding the first layer to said second layer; andbonding the second layer to the third layer.
 15. The method of claim 14,further comprising the step of forming the third layer as a batt. 16.The method of claim 15, further comprising the step of forming a smoothsurface on said batt.
 17. The method of claim 14, wherein the bonding ofthe first and second layers is a lamination process.
 18. The method ofclaim 14, wherein the bonding of the second and third layers is alamination process.
 19. The method of claim 14, further comprising thestep of providing a second functional fabric layer.
 20. The method ofclaim 19, wherein the second functional fabric layer is laminated to thebreathable water repellant insulating layer.